Product for inhibiting the attack on metals by acids or salts and its applications



Q Patented May 30, i939 ICE PRODUCT FOR INHIBITING THE ATTACK N METALSBY ACIDS OB SALTS AND ITS APPLICATIONS Jacques Edouard Julien GeorgesMascr,

Premery, France, assignor to Etabllssements Lambiotte Freres Premery(Nievre), France, a

corporation of ljrance ,No Application November 17, 1936,

Serial No. 111,336. 1935 6 Claims.

It is known that metals are attacked by acids in the absence of oxygenunder conditions which depend both upon the nature of the metal and uponthat or the acid.

In principle for a given acid the attack is more rapid, that is to saythe dissolution is more rapid,

'if the inetal is situated lower in the scale of so- .Now according tothe present invention it has been observed the oils obtained in thecarbonization of wood have a very much greater inhibiting power forequal weight of the product employed, than that of all knowncompositions and an efiicaciousness which is quite general in all cases.

It is known that in the carbonization of wood a pyroligneous liquid isobtained which by distillation gives crude wood spirit which containsbesides methanol, methyl acetate, acetone and allyl alcohol, a fractionof oils which will be referred to as crude wood spirit oils, which maybe separated either by rectification or by dilution of the crude woodspirit with water.

These oils have a density between 0.890 and 0.935, most generally 0.910to 0.925. They distil from 50-220" C. 80-90% passingon the average froml-130 C. to 205-210 C. They are rich in ketonic products (30-45%calculated as acetone) and allyl compounds (IO-30% calculated asallylalcohol) hydes, diketones, alcohols, hydrocarbons, furane andcyclopentane derivatives, amines, and other products which are unknownor not identified at present but which contribute for their part totliil: special and characteristic properties of these 0 According to thepresent invention the unexpected'discovery has been made that these oilsand all the fractions which are still very complex and which can beseparated therefrom in one way or another exhibit inhibitory propertiestowards the attack on metals by acids or strongly dissociatedsadts.

' They may thus be very usefully employed for To sum up, these oilscontain ketones, aide- In France December 17,.

preventing if not. entirely at least almost entirely attack on a metalwhenever the latter is put into contact with an acid or a salt whichattacks it. This is particularly the 'case with cleaning, pickling, ortreatment of metals by acids, and in the case of scaling metallicsurfaces by acids. It is sufiicient to mix the oils with the pickling orscaling baths used, and their presence in these baths does not at allalter the solubility in the acid of the oxide or scale. It shouldlikewise vbe added that their wetting power facilitates their action andrenders it regular.

But though these crude wood oils may be used for this purpose they havethe disadvantage of not being entirely soluble in aqueous solutions ofacids and of consequently giving rise to a greater or less degree toblackish tars which are deposited upon the walls of the receptacles. 1

To remedy this disadvantage it has been observed that' it is sufiicientto destroy by resinifyingthe unstable components of the oils, forexample by bringing them to boiling in an acid medium, then inextractingfrom the oils thus treated the active, soluble and stableproducts' is added 1 part by volume of 7% hydrochloric.

acid or 10% sulphuric acid. The mixture is brought to boiling under areflux for 10 hours.

After cooling the lower aqueous layer representing1.05 to 1.10 parts byvolume is decanted,

clarified, and constitutes a stable extract containing 7-10% ofdissolved active crude wood spirit oils.

The residual oil about 0.9 part by volume may be extracted again byagitation in the cold with an equal volume of acid as described aboveand give a new quantity of extract only half as rich as the aboveextract.

Thus systematic extractions may be combined on this principle. 1.

A practically deodorized extract may be ob tained by eliminating fromthe above extracts by distillation with a column, a first fraction of 10which entrains the most volatile and strongly odoriferous constituents.e

' This distilled fracthn constitutes moreover a I stable and solublevery strongly active extract.

In. the following there are given a certain number of results ofexperiments with extracts of wood oils mixed with baths for pickling orscaling.

1. Pickling baths.

The tests were eflected upon portions of drawn iron tube and pickled andcleaned.

"The weight losses per square meter per hour were for an averageduration oi- 60 hours 250 hours I (a) Treatment in the'cold (W C.) witha solution a pure hydrochloric acid with 23' aroma of Cl per 100 cco.

Pure hydrochloric acid alone 389 Pure hydrochloric acid+1% erseniousanhydride 332 Pure hydrochloric acid+l% oi aniline.--" 179 Purehydrochloric acid+5% oi iormol 6. 17 8. 02 Pure hydroc on +l% of crudewood s 2.09 8.62 Pure hydrochloric acid+107 of a 69% sulphuric acidextract of dissolved wood oils 2.80 4.13 Pure hydrochloric acid+l0% of a710% hydrochloric acid extract oi dissolved wood oils 2. 25 3. 43

(0) Treatment in the cold (20 C.) with a solution of pure sulphuric acidwith 30.6 grams per 100 coo.

Pure sulphuric acid alone; 262 Pure sulphuric acid+l% oi anilin 155 Puresulphuric acid+l% oi iormol (30%)-.. 5. 37 Pure sulphuric acid saturatedwith arsenious anhydride 0. 792 1. 31 Pure sulphuric acid+10% of a 6-8%sulphuric acid extract of dissolved wood oils. 0. 540 0. 615 Puresulphuric aci d+10% of a 3-6% deodorised sulphuric acid extract ofdissolved wood oils 0.885 1. 87

(4:) Hot treatment (6' 0 C.) with (isolation of pure sulphuric acid with21.91 gram per 100 cce.

Pure sulphuric acid alone 1030 Pure sulphuric acid+l% aniline 843 Puresulphur c'acid-l-1% iormol (30%).--. 107 Pure sulphuric acid+l0% of all-9% sulphuric acid extract of dissolved wood oils 28 Pure sulphuricacid-H0 of a 845% sulphuric acid extract of lved wood 0ils 77 2. Scalingbaths. v The scaling solutions employed all contained 3.5 grams ofgaseous HCl per 100 ccs.

The weight losses in grams per square meter per hour were for an averageduration el- 24 hours 100 hours (a) Upon portions ofdraum iron tubepickled and cleaned A Pure hydrochloric acid alone 78. 2 Water+l0% ofcommercial scaling compound with a bimis oi araenious anhydride 2.80 6.0Water+10% of commercial scaling compound with a basis of formol 0. 4050. 602 Pure hydrochloric acid+1% of a 7-10% hydrochloric acid extract ofdissolved wood oils 0. 501

The weight losses in grams square meter per hour were for an averageduration of- (b) Upon crude sheet of pure aluminium for industrialapparatus A.

24 hours 48 hours Pure hydrochloric acid alone 3. 99 4. 68 Water+l0%commercial scaling compound with a basis oi arsenious anhydride. 5. 8817. 4 Water+10% of a commercial scaling pound with a basis oi formol 27.2 13. 4 Pure hydrochloric midi-1% oi formol (30%) 10. 6 11.4 -Purehydrochloric acid+l%.ot a 7-10% hydrochloric acid extract oi\ dissolvedwood oils 0. 89 0. 96 Pure hydrochloric acid+10% of a 7-10% hydrochloricacid extract of dissolved wood oils. 0. 28 0. 17

(c) Upon crude zinc sheet 2 hours 48 hours Pure hydrochloric acid alone800 Water+l0% oi commercial scaling compound with a basis of arseniousanhydride 2070 Weter+10% commercial scaling compound with basis ofiorinol 930 Pure hydrochloric acid+1% formol (30%).- 900 Purehydrochloric acid-+10% of a 1015% hydrochloric acid extract of dissolvedwood oils 0.74 0.29

For pickling and scaling baths the results are substantially the samewith the ordinary acids of commerce more or less charged withimpurities.

It has moreover been observed that even in the presence of acceleratingimpurities like arsenious anhydride the wood oils or their extractsmaintain practically the whole of their efllciency.

What I claim is:

1. A metal treating bath comprising a diluted mineral acid and as aninhibitor product preventing the attack of the 'metal itself a lowproportion of crude wood spirit oils arising from the carbonization ofwood.

2. A metal pickling bath comprising a diluted mineral acid and as aninhibitor product preventing the attack of the metal itself a lowproportion of crude wood spirit oils arising from carbonization of wood.I

3. A. metal scaling bathcomprising a diluted mineral acid and as aninhibitor product preventing the attack of the metal itself a lowproportion of crude wood spirit-oils arising from carbonization or wood.

venting the attack of the metal itself a low proportion of crude woodspirit oils arising from the carbonization of wood.

6. A metal treating bath comprising a diluted mineral acid and as aninhibitor product preventing the attack of the metal itself a lowproportion of an aqueous extract of wood spirit oils. JACQUES EDOUARDJULIEN GEORGES MASCRE.

